The biggest draw is seemingly not the fact that you don't need a visa to live and work on the ship, but rather entrepreneurs are coming for the "awesome startup and technology-oriented space." The second most critical element for startups was the close proximity to Silicon Valley's venture capital scene.
Rent to live on the ship is about as much as a single person living in San Francisco has to pay: around $1600 a month. That is, if you're willing to bunk up. The price includes both living and office space, but will range from $1200 for a shared cabin, and runs up to $3000 for a "top-tier single" cabin. Ferries will shuttle entrepreneurs from the ship to Silicon Valley daily, and Blueseed says it will help those from outside the US enter. Blueseed is also looking for incubators who are interested in helping the startups.
"Startup ship of dreams": libertarian fantasy hootenanny meets rusty, smelly "hackerspace" dorm room.